1. Field of the Invention
The present invention relates to a hydraulic power brake device for wheeled vehicles, and more particularly to a hydraulic brake booster of the type utilizing pressurized fluid supplied to a hydraulically operated device such as a power steering device and the like.
2. Description of the Prior Art
As a conventional brake booster of this type, there has been introduced a hydraulic brake booster in which a first flow regulating valve is adapted to rapidly increase the pressure in a power chamber in response to the braking operation and a second flow regulating valve is adapted to ensure supply of the pressurized fluid to the hydraulically operated device. In the above-noted brake booster, the first flow regulating valve includes a spring loaded valve member which is operated by a control piston or a power piston to block the flow of fluid supplied into the power chamber in response to the braking operation. The valve member is also provided thereon with an orifice to throttle the flow of fluid supplied into the power chamber so as to increase the pressure in the power chamber. This means that the assembly of the valve member is complicated and the control piston or the power piston remains in a position with a large reaction force against loading of the valve member. It is, therefore, observed that production cost of the booster becomes high and smooth operation of the booster may not be assured.